Characterization of a Chitosan-like Bioflocculant BF01314 produced by Citrobacter youngae in Kaolin Flocculation

摘要

Many bacterial strains from the genus Citrobacter have been reported to produce a soluble chitosan-like bioflocculant with strong flocculating activity. This study investigated the flocculation characteristics of a novel chitosan-like bioflocculant (BF01314) produced by Citrobacter youngae GTC 01314 in kaolin using the 'flocculating titer' method. High flocculating activity of more than 95% was recorded under the twofold serial dilution factors of 2~3 to 2~6 of the crude bioflocculant. At this broad 'flocculation window', pH of the suspension changed from 7.83 to 6.53 while zeta potential of the suspension experienced charge neutralisation and charge reversal, from -4.26 mV to 6.97 mV (at 2~5 dilution), then dropped to -15.7 mV (at 2~6 dilution). BF01314 was able to demonstrate high flocculating activity of more than 90% under acidic condition between pH 2 to 6. The bioflocculant was also found to retain high thermal stability up to 100°C for 30 minutes. The effectiveness of BF01314 in kaolin flocculation suggests its potential application in removal of suspended solids in wastewater treatment. Acknowledgement: The authors acknowledge the financial support from the Ministry of Higher Education Malaysia under the Fundamental Research Grant Scheme (FRGS/1/2017/TK02/CURTIN/03/1).